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//==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This abstract class defines the interface for Objective-C runtime-specific
// code generation. It provides some concrete helper methods for functionality
// shared between all (or most) of the Objective-C runtimes supported by clang.
#include "CGObjCRuntime.h"
#include "CGCleanup.h"
#include "CGRecordLayout.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtObjC.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "llvm/IR/CallSite.h"
using namespace clang;
using namespace CodeGen;
static uint64_t LookupFieldBitOffset(CodeGen::CodeGenModule &CGM,
const ObjCInterfaceDecl *OID,
const ObjCImplementationDecl *ID,
const ObjCIvarDecl *Ivar) {
const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
// FIXME: We should eliminate the need to have ObjCImplementationDecl passed
// in here; it should never be necessary because that should be the lexical
// decl context for the ivar.
// If we know have an implementation (and the ivar is in it) then
// look up in the implementation layout.
const ASTRecordLayout *RL;
if (ID && declaresSameEntity(ID->getClassInterface(), Container))
RL = &CGM.getContext().getASTObjCImplementationLayout(ID);
RL = &CGM.getContext().getASTObjCInterfaceLayout(Container);
// Compute field index.
// FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
// implemented. This should be fixed to get the information from the layout
// directly.
unsigned Index = 0;
for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
IVD; IVD = IVD->getNextIvar()) {
if (Ivar == IVD)
assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
return RL->getFieldOffset(Index);
uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
const ObjCInterfaceDecl *OID,
const ObjCIvarDecl *Ivar) {
return LookupFieldBitOffset(CGM, OID, 0, Ivar) /
uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
const ObjCImplementationDecl *OID,
const ObjCIvarDecl *Ivar) {
return LookupFieldBitOffset(CGM, OID->getClassInterface(), OID, Ivar) /
unsigned CGObjCRuntime::ComputeBitfieldBitOffset(
CodeGen::CodeGenModule &CGM,
const ObjCInterfaceDecl *ID,
const ObjCIvarDecl *Ivar) {
return LookupFieldBitOffset(CGM, ID, ID->getImplementation(), Ivar);
LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
const ObjCInterfaceDecl *OID,
llvm::Value *BaseValue,
const ObjCIvarDecl *Ivar,
unsigned CVRQualifiers,
llvm::Value *Offset) {
// Compute (type*) ( (char *) BaseValue + Offset)
QualType IvarTy = Ivar->getType();
llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
if (!Ivar->isBitField()) {
V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
return LV;
// We need to compute an access strategy for this bit-field. We are given the
// offset to the first byte in the bit-field, the sub-byte offset is taken
// from the original layout. We reuse the normal bit-field access strategy by
// treating this as an access to a struct where the bit-field is in byte 0,
// and adjust the containing type size as appropriate.
// FIXME: Note that currently we make a very conservative estimate of the
// alignment of the bit-field, because (a) it is not clear what guarantees the
// runtime makes us, and (b) we don't have a way to specify that the struct is
// at an alignment plus offset.
// Note, there is a subtle invariant here: we can only call this routine on
// non-synthesized ivars but we may be called for synthesized ivars. However,
// a synthesized ivar can never be a bit-field, so this is safe.
uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar);
uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
CharUnits StorageSize =
llvm::RoundUpToAlignment(BitOffset + BitFieldSize, AlignmentBits));
CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
// Allocate a new CGBitFieldInfo object to describe this access.
// FIXME: This is incredibly wasteful, these should be uniqued or part of some
// layout object. However, this is blocked on other cleanups to the
// Objective-C code, so for now we just live with allocating a bunch of these
// objects.
CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
V = CGF.Builder.CreateBitCast(V,
return LValue::MakeBitfield(V, *Info,
namespace {
struct CatchHandler {
const VarDecl *Variable;
const Stmt *Body;
llvm::BasicBlock *Block;
llvm::Value *TypeInfo;
struct CallObjCEndCatch : EHScopeStack::Cleanup {
CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
MightThrow(MightThrow), Fn(Fn) {}
bool MightThrow;
llvm::Value *Fn;
void Emit(CodeGenFunction &CGF, Flags flags) override {
if (!MightThrow) {
void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
const ObjCAtTryStmt &S,
llvm::Constant *beginCatchFn,
llvm::Constant *endCatchFn,
llvm::Constant *exceptionRethrowFn) {
// Jump destination for falling out of catch bodies.
CodeGenFunction::JumpDest Cont;
if (S.getNumCatchStmts())
Cont = CGF.getJumpDestInCurrentScope("eh.cont");
CodeGenFunction::FinallyInfo FinallyInfo;
if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
FinallyInfo.enter(CGF, Finally->getFinallyBody(),
beginCatchFn, endCatchFn, exceptionRethrowFn);
SmallVector<CatchHandler, 8> Handlers;
// Enter the catch, if there is one.
if (S.getNumCatchStmts()) {
for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
CatchHandler &Handler = Handlers.back();
Handler.Variable = CatchDecl;
Handler.Body = CatchStmt->getCatchBody();
Handler.Block = CGF.createBasicBlock("catch");
// @catch(...) always matches.
if (!CatchDecl) {
Handler.TypeInfo = 0; // catch-all
// Don't consider any other catches.
Handler.TypeInfo = GetEHType(CatchDecl->getType());
EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
// Emit the try body.
// Leave the try.
if (S.getNumCatchStmts())
// Remember where we were.
CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
// Emit the handlers.
for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
CatchHandler &Handler = Handlers[I];
llvm::Value *RawExn = CGF.getExceptionFromSlot();
// Enter the catch.
llvm::Value *Exn = RawExn;
if (beginCatchFn) {
Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
if (endCatchFn) {
// Add a cleanup to leave the catch.
bool EndCatchMightThrow = (Handler.Variable == 0);
// Bind the catch parameter if it exists.
if (const VarDecl *CatchParam = Handler.Variable) {
llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
llvm::Value *CatchParamAddr = CGF.GetAddrOfLocalVar(CatchParam);
switch (CatchParam->getType().getQualifiers().getObjCLifetime()) {
case Qualifiers::OCL_Strong:
CastExn = CGF.EmitARCRetainNonBlock(CastExn);
// fallthrough
case Qualifiers::OCL_None:
case Qualifiers::OCL_ExplicitNone:
case Qualifiers::OCL_Autoreleasing:
CGF.Builder.CreateStore(CastExn, CatchParamAddr);
case Qualifiers::OCL_Weak:
CGF.EmitARCInitWeak(CatchParamAddr, CastExn);
// Leave any cleanups associated with the catch.
// Go back to the try-statement fallthrough.
// Pop out of the finally.
if (S.getFinallyStmt())
if (Cont.isValid())
namespace {
struct CallSyncExit : EHScopeStack::Cleanup {
llvm::Value *SyncExitFn;
llvm::Value *SyncArg;
CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
: SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
const ObjCAtSynchronizedStmt &S,
llvm::Function *syncEnterFn,
llvm::Function *syncExitFn) {
CodeGenFunction::RunCleanupsScope cleanups(CGF);
// Evaluate the lock operand. This is guaranteed to dominate the
// ARC release and lock-release cleanups.
const Expr *lockExpr = S.getSynchExpr();
llvm::Value *lock;
if (CGF.getLangOpts().ObjCAutoRefCount) {
lock = CGF.EmitARCRetainScalarExpr(lockExpr);
lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
} else {
lock = CGF.EmitScalarExpr(lockExpr);
lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
// Acquire the lock.
CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
// Register an all-paths cleanup to release the lock.
CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
// Emit the body of the statement.
/// Compute the pointer-to-function type to which a message send
/// should be casted in order to correctly call the given method
/// with the given arguments.
/// \param method - may be null
/// \param resultType - the result type to use if there's no method
/// \param callArgs - the actual arguments, including implicit ones
CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
QualType resultType,
CallArgList &callArgs) {
// If there's a method, use information from that.
if (method) {
const CGFunctionInfo &signature =
CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
llvm::PointerType *signatureType =
// If that's not variadic, there's no need to recompute the ABI
// arrangement.
if (!signature.isVariadic())
return MessageSendInfo(signature, signatureType);
// Otherwise, there is.
FunctionType::ExtInfo einfo = signature.getExtInfo();
const CGFunctionInfo &argsInfo =
CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs, einfo,
return MessageSendInfo(argsInfo, signatureType);
// There's no method; just use a default CC.
const CGFunctionInfo &argsInfo =
CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs,
// Derive the signature to call from that.
llvm::PointerType *signatureType =
return MessageSendInfo(argsInfo, signatureType);